1. Field of the Invention
The present invention relates to nanotweezers that can grip and release nano-substances having a nano-scale size by opening and closing a plurality of nanotubes. More specifically, the present invention relates to a nano-substance mass measurement method and apparatus which can measure the mass of gripped nano-substances by measuring resonance frequencies of the gripping portion of the nanotweezers before and after the gripping of the nano-substances.
2. Prior Art
Generally, mass analysis methods are used as methods for measuring the mass of extremely small substances such as atoms, molecules, etc. In such mass analysis methods, a sample is ionized, and the ions are accelerated by means of an electric field so that the traveling velocity is caused to vary according to the mass. Then, the ion current is separated according to the specific charge e/m or m/e by rotation in a magnetic field, and the mass of the ions is deduced from the respective peaks in the mass spectrum.
The mass analysis method has the advantage of allowing precise measurements of the mass of relatively light substances such as atoms and molecules. However, this method is unsuitable for measuring the mass of nano-substances such as extremely small particles formed by the aggregation of 100 to 10,000 atoms.
The mass of such nano-substances is larger than the mass of atoms. Accordingly, even if these nano-substances are ionized by electron bombardment or high-frequency spark discharge, an ultra-high-intensity electric field is required in order to cause the ions to travel through space; and in order to realize such an electric field, it is inevitable that the apparatus to be used becomes excessively large in size. Furthermore, even if it is possible to cause the ions to travel through space, since the ions have a large inertia, an extremely large magnetic field is required for rotation of the ions. Consequently, the overall size of the apparatus used needs to be extremely large as in the case described above.
Devices that create heavy ion beams have been realized in research of atomic nuclei, etc. However, these devices are extremely large in size, and thus an extremely large apparatus is thus required even at the level of heavy ions. Accordingly, in cases where the mass of nano-substances or nano-particles that are even larger than heavy ions are to be measured by ionization, such measurements are virtually impossible when the above-described mass analysis method is used in terms of both cost and practicality.
Accordingly, the object of the present invention is to provide a nano-substance mass measurement method and apparatus in which, without using an ionizing device, electric field accelerating device or magnetic field rotating device, the mass of nano-substances is obtained in an extremely simple manner by way of griping nano-substances with nanotweezers that have nanotubes etc. at the tip ends thereof and measuring resonance frequencies of the nanotweezers before and after such gripping.
The present invention is a nano-substance mass measurement method characterized in that, with the use of nanotweezers that are capable of gripping and releasing nano-size nano-substances, a nano-substances is gripped by the nanotweezer gripping portion of the nanotweezers, the nanotweezer gripping portion in this gripping state is caused to resonate, the resulting characteristic frequency fm is measured, and the mass of the gripped nano-substance is obtained by comparing two characteristic frequencies fm and fo where fo is the characteristic frequency of the gripping portion of the nanotweezers which is in a state that no nano-substance is gripped.
In the above nano-substance mass measurement method of the present invention, the nanotweezer gripping portion is formed by the tip end portions of a plurality of nanotubes.
Furthermore, in the nano-substance mass measurement method according to the present invention, an external electrode is caused to approach the gripping portion of the nanotweezers, and an AC voltage is applied across the gripping portion of the nanotweezers and the external electrode so that the gripping portion of the nanotweezers is caused to resonate by AC electrostatic induction, thus measuring the characteristic frequencies fo and fm.
Also in the nano-substance mass measurement method of the present invention, a piezo-electric element is provided in the nanotweezer main body which has the nanotweezer gripping portion on the tip end, and the nanotweezer gripping portion is caused to resonate by applying an AC voltage to this piezo-electric element, thus measuring the characteristic frequencies fo and fm.
The present invention is also a nano-substance mass measuring apparatus which is comprised of: a nanotweezer main body to which the base end portions of a plurality of nanotubes are fastened, a nanotweezer gripping portion that is formed by the tip end portions of the nanotubes, a means which controls the nanotweezer gripping portion so that the gripping portion can be freely opened and closed, an external electrode that is disposed in close proximity to the nanotweezer gripping portion, and an AC power supply which applies an AC voltage used for resonance across the nanotweezer gripping portion and the external electrode.
Furthermore, the present invention is a nano-substance mass measuring apparatus which is comprised of a nanotweezer main body to which the base end portions of a plurality of nanotubes are fastened, a nanotweezer gripping portion that is formed by the tip end portions of the nanotubes, a means which controls the nanotweezer gripping portion so that the gripping portion can be freely opened and closed, a piezo-electric element which is provided in the nanotweezers, and an AC power supply which applies an AC voltage used for resonance to the piezo-electric element.